1. Field of the Invention
The invention relates to machine vision processing of image data and, more specifically, to separating pixels of an image into regions based on multiple planes of measurement data.
2. Description of the Related Art
In image processing it is desirable to know the qualitative aspects of a surface, which may be independently important or may provide important information for later processing. For example, whether the surface contains a scratch or pitting, or where a particular material occurs in or on the surface, can be important for quality control in mass production applications.
Heretofore, no strong technology existed to qualitatively evaluate data. One common machine vision technique separates pixels into regions based on intensity thresholds. Basically, the processing compares the value of each pixel of an image to a reference value. If the pixel value is above the reference value, the pixel is determined to be in one region of the surface, and if the pixel value is below or equal to the reference value, the pixel is determined to be in a second region of the surface. The use of a single image to identify regions causes errors where regions overlap. In addition, separating pixels at the edge of a surface region using thresholding techniques tends to be inaccurate.
Sometimes multiple images of the surface are obtained and compared to more than one reference value. However, even in the presence of multiple measurement thresholds, the thresholds are applied to the individual measurements, and then the result is analyzed. Thus, thresholding techniques do not typically allow separating regions of a surface from one another that overlap one another when measured by either image alone.